The 2/1/3 superconductor, which has the formula YBa.sub.2 Cu.sub.3 O.sub.7-x, wherein x is equal to or less than 0.3, is well known to those skilled in the art. Thus, e.g., it is described in an article by M. K. Wu, et al. appearing in Physical Review Letters 58, 908 (1987).
The 2/1/3 superconductor is known to be highly sensitive to water. Thus, in an article by M. F. Yan et al. entitled "Water Interaction with the Superconducting YBa.sub.2 Cu.sub.3 O.sub.7 Phase," Applied Physics Letters 51 (1987), at pages 532-534, the authors disclose that the 2/1/3 superconductor is ". . . highly sensitive to water and water vapor. . . ", and that its ". . . superconductivity is also greatly degraded by the interaction with water and humid air." In order to overcome this problem, the authors suggest that: "Applications of this and similar materials which involve a nonequilibrium oxidation state will probably require protection from ambient water."
Other authors have also discussed the adverse effects of water upon the properties of the 2/1/3 superconductor. See, e.g., an article by K. G. Frase et al. entitled "Environmental and Solvent Effects on Yttrium Barium Cuprate. . . ," Advanced Ceramic Materials, Vol. 2, No. 3B, Special Issue, 1987. Also see an article by I. Nakada et al. entitled "Two crystal Phases in the Superconducting Ba-Y-Cu-O Systems and Their Reactivity to Water," Japanese Journal of Applied Physics, Issue No. 5, May, 1987, pages L697-L698.
It is an object of this invention to provide a 2/1/3 superconductor which does not decompose substantially when exposed to water.